In this article, a cylindrical direct‐current triboelectric nanogenerator (DC‐TENG) that can generate an almost constant current output with a low crest factor by phase coupling is reported for the first time. Here, the influence of phases (P) and groups (G) on the DC‐TENG is investigated. Experiments show that the crest factor of current, significantly decreases as the phases increase, and the output performance significantly increases as the groups increase. One phase triboelectric power‐generating unit of the DC‐TENG with three‐phase and five‐group (3P5G) produces an open‐circuit voltage of 149.5 V, short‐circuit current 7.3 μA, and transferred charge of 56.7 nC at 600 rpm. The DC‐TENG can produce a coupling current of 21.6 μA and the average output power of 2.04 mW after each phase output is rectified and superimposed. Additionally, the crest factor of output current is reduced to 1.08, and the high‐performance characteristics of an almost constant direct‐current is achieved. The research is of considerable significance to the practical applications of TENGs in powering sensors of low consumption.
We present a statistical study of a sample of 17 hub-filament-system (HFS) clouds of high-mass star formation using high-angular resolution (∼1–2″) ALMA 1.3 mm and 3 mm continuum data. The sample includes 8 infrared (IR)-dark and 9 IR-bright types, which correspond to an evolutionary sequence from the IR-dark to IR-bright stage. The central massive clumps and their associated most massive cores are observed to follow a trend of increasing mass (M) and mass surface density (Σ) with evolution from IR-dark to IR-bright stage. In addition, a mass-segregated cluster of young stellar objects (YSOs) are revealed in both IR-dark and IR-bright HFSs with massive YSOs located in the hub and the population of low-mass YSOs distributed over larger areas. Moreover, outflow feedback in all HFSs are found to escape preferentially through the inter-filamentary diffuse cavities, suggesting that outflows would render a limited effect on the disruption of the HFSs and ongoing high-mass star formation therein. From the above observations, we suggest that high-mass star formation in the HFSs can be described by a multi-scale mass accretion/transfer scenario, from hub-composing filaments through clumps down to cores, that can naturally lead to a mass-segregated cluster of stars.
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